Hi, Agentgnat! I think this is a really old thread, so probably not!!
Are you sure you want to buy one? They are so easy to make! I got all jazzed up with #2 and had him in ours on his first day out!
It worked, even though people did think I was INSANE and maybe even a little mean.
If you are starting with a teeny tiny baby, you just need the edges high enough to let babe bump into it and get stopped, I think it's actually good to keep it low enough that they can lift their little heads and see over the edge.
We used cheap wood, foam covering, staples, and a soft sheet. We didn't make it slope at all, I just propped it up with pillows or held it in my lap at first - he was doing it fine totally flat pretty quickly. Can we post pics here? I could snap a shot of ours.
Anyway, after he outgrew that mini-track, I didn't really ever see a need for another one - I'm sure they would be just as easy to make on the larger scale though!!